This invention relates to a cooling system for a marine propulsion engine and more particularly to an improved arrangement for precluding corrosion or contamination of the cooling system during periods when the watercraft is not in use.
As is well known, many forms of marine propulsion units employ internal combustion engines having liquid cooling jackets through which coolant from the body of water in which the watercraft is operating is circulated. Many times, as with inboard/outboard drives, the engine and its cooling jacket are disposed in the hull of the watercraft at a level below the water level, even when the watercraft is stationery. As a result of this, when the engine is not operating, coolant can flow by gravity into the cooling jacket or, alternatively, will be retained in the cooling jacket. This can present some problems, particularly when operating in marine environments wherein the coolant may comprise salt water. The retention of salt water in the engine cooling jacket can give rise to corrosion and other problems with respect to encrustation and the like.
Although arrangements have been provided for pumping water out of the bilge or other areas associated with the engine when not in use, the previously proposed systems have not provided any arrangement wherein the cooling jacket itself may be emptied of coolant. Hence, the problems aforenoted will exist.
It is, therefore, a principal object of this invention to provide an improved cooling system for a marine propulsion engine wherein the engine cooling jacket may be drained during periods of non-use.
It is a further object of this invention to provide an improved arrangement for the cooling jacket of an inboard engine wherein the cooling jacket may be completely drained when the boat is in a period of non-use.